[ImgBot] optimizes images

*Total -- 8.95kb -> 8.83kb (1.26%)

/media/badges/rpi-3-32px.png -- 2.28kb -> 2.23kb (2.14%)
/media/badges/rpi-0-32px.png -- 2.24kb -> 2.21kb (1.13%)
/media/badges/rpi-2+-32px.png -- 2.24kb -> 2.22kb (1.05%)
/media/badges/rpi-2-32px.png -- 2.18kb -> 2.17kb (0.67%)

Author: ImgBotApp